Aortic stenosis is the malformation, narrowing or obstruction of the aortic valve, which prevents it from opening properly and prevents the normal flow of blood from the aorta to the left ventricle.
Atrial Septal Defect
In a heart with an Atrial Septal Defect (ASD) there is communication between the right and left atria which causes a left to right shunting of blood due to the higher pressure in the pulmonary circulatory system. Because of this there is a mixing of oxygenated and deoxygenated blood. The right atrium and ventricle may enlarge due to the higher volume of blood they must handle.
Atrioventricular Canal Defect
Is a large hole in the center of the heart where the wall between the upper chambers joins the wall between the lower chambers. The tricuspid and mitral valves aren't formed properly, a single large valve crosses the defect. The opening in the center of the heart lets oxygen rich blood pass to the heart's right side and mix with venous blood, then go back to the lungs. The heart has to pump an extra amount of blood and may enlarge.
Coarctation of the Aorta
In a coarctation of the aorta, the aorta is constricted, obstructing blood flow from the heart to the rest of the body. This can result in low blood pressure and low blood flow past the coarctation, and high blood pressure on the side that is closer to the heart. This defect can result in high blood pressure in the upper body and arms and low blood pressure in the lower body and legs.
The primary abnormality in Ebstein’s Anomaly is of the tricuspid valve, the valve which lies between the right atrium and right ventricle. While there is free flow of blood forward across the tricuspid valve to the right ventricle, the deformed tricuspid valve allows a large amount of blood to flow backwards from the right ventricle to right atrium when the right ventricle contracts.
Hypoplastic Left Heart Syndrome
In Hypoplastic Left Heart Syndrome the left side of the heart is poorly formed and cannot handle the main circulation to the body. The left ventricle and aorta are abnormally small (hypoplastic). This is amongst the most severe forms of heart defects. Most babies are very ill in the early days of life and need urgent surgery to survive.
Patent Ductus Arteriosus
Everyone is born with ductus arteriosus: a small opening between the pulmonary artery and the aorta. Usually this opening closes a couple hours after birth. In some cases, especially premature babies, the opening fails to close, allowing blood that should go through the aorta to the body to go back to the lungs. Symptoms include slow growth, tiring quickly and rapid breathing.
Stenosis means narrowing. The pulmonary valve normally has three leaflets and may have only one or two leaflets, or three leaflets which may be malformed or completely stuck together. These abnormal leaflets do not open properly, causing a narrowing of the valve. The right ventricle works harder to pump blood past the deformed valve. The extra stress put on the right ventricle may cause it to enlarge.
Pulmonary stenosis can vary from mild to severe. Children with mild pulmonary stenosis usually have no symptoms. If the stenosis is very mild, surgery is usually not needed. Severe stenosis can cause symptoms in infancy such as rapid breathing, poor feeding, and no energy. In some cases, cyanosis (bluish color of lips, skin and nails) may develop.
Tetrology of Fallot
The combination of a ventricular septal defect with pulmonary stenosis and with righ ventricular hypertrophy is termed "Tetralogy of Fallot". Blood flow to the lungs is obstructed and diverted through the VSD to the aorta. Blood flow to the lungs is reduced and the child appears 'Blue' (cyanosed).
Transposition of the Great Arteries
In TGA, the normal position of the arteries is reversed. The aorta comes out of the right ventricle (instead of the left), and the pulmonary artery comes out of the left ventricle. This means that the right ventricle pumps blood to the body and the left ventricle pumps blood to the lungs. The problem with this is that oxygen-rich blood returns to the lungs while oxygen-poor blood gets carried to the rest of the body.
The only way for oxygen-rich blood to reach the body is through another defect that connects the two routes. An atrial septal defect allows the exchange of blood between the two atria, a ventricular septal defect allows the exchange of blood between the two ventricles, and a patent ductus arteriosus connects the pulmonary artery and the aorta.
Tricuspid atresia means that the tricuspid valve didn't develop normally. Because of this, the right ventricle may also not develop properly, and there may be only a single ventricle. Because there is no tricuspid valve, blue blood returning to the heart from the body cannot enter the right ventricle. This blue blood then shunts across an atrial septal defect to the left atrium, and mixes with the red blood returning from the lungs. The mixture of blue and red in the left atrium enters the ventricular septal defect and from there is sent to the aorta and the pulmonary artery.
Ventricular Septal Defect
The most common congenital heart defect is the ventricular septal defect or VSD. This is what many people call the "hole-in-the-heart." The ventricular septum is the wall that separates the right and left sides of the heart. A VSD is a hole in the wall between the two ventricles. Usually, blood enters the right side of the heart stays on the right side (low oxygen blood), and blood on the left side stays on the left side (oxygenated blood) which is then pumped to the rest of the body. When a defect or "hole" is present between the ventricles, blood from the left side of the heart is forced through the defect to the right side every time the heart beats. It then goes back to the lungs even though it is already rich in oxygen. Because of this, blood that is not oxygenated cannot get to the lungs.